The ability of a memory device to store and accurately retain data is important. Bit errors which compromise the integrity of the stored data become increasingly problematic as memory devices continue to become smaller with the scaling of process technology. Bit errors may also be problematic in Multi Level Cell (MLC) memories where more than one bit is stored in a single memory cell.
The bit error rate (BER) for a memory device is non-static, and can change over time as the memory is used and as the ability of the memory cells to retain charge decreases.